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Aquaponics: Root-bound Tomatoes

We’ve had a terrific season of growing tomatoes for the last eight or nine months and right through into the Queensland winter. The one vine we had just kept producing massive amount of tomatoes month after month.
I must admit being a bit cautious about what the flavour of an aquaponically grown tomato would be like.
Would it tasty watery and lacking in flavour? We can assure you if you choose a good old fashioned variety the tomatoes you grow will outclass anything you can buy in the shops. Hands down the flavour of aquaponically grown tomatoes are exquisite.

If you plant a boring tasteless hybrid plant – and we once did – you will get a tasteless hybrid tomato. Aquaponics can grow tomatoes very well but it can’t work miracles, so choose your tomato variety carefully before planting for good results.

A good tip is to not over-plant your grow beds with tomatoes.

You only need one or two tomato plants per system to feed your family. Sometimes less is more.

But there is a trade-off with tomatoes grown in aquaponics and that is you will get rampant growth. Massive vines baring large full flavoured fruit comes at a cost.

Massive root-balls!

The tell tale signs that things are powering along below the pebbles is that the water bringing in all that lovely fish nutrient will start to pool on top of the gravel or clay pebbles.

The water doesn’t seem to sink or disappear but spreads out. Water pooling like this can indicate you have either far too much water running into your grow-beds or if there’s a tomato planted nearby. You have a root-ball problem.

Its not really a problem that worries us greatly if we are getting good growth and plenty of fruit. But after a while you need to do some maintenance because the root-ball will crowd out other plants growing nearby and you’ll notice your tomato vine is just getting rampant and out of control.

Massive tomato rootball spreads out causing water to pool in the growbed.

So reluctantly we decided to rip the plant out.

It had still plenty of green and ripe tomatoes coming along but the system badly needed some attention.

Lifting the plant out of the grow bed revealed that the root-ball does not grow down to the bottom of the trough but spreads out laterally like a thick carpet of mulch.

Any compost worms you’ve thrown into the system will adhere in this layer feeding off bacteria.

Below the root-ball the water will be a muddy brown colour and free of obstruction.

The roots will smother the pebbles and freeing them can be difficult.

A good technique is to use a plastic laundry basket to wash and drain the roots, free the pebbles and allowing them to be reintroduced back into the system.

Some people just let them dry out in the sun for a few days, loosening the roots, making them more brittle and easier to dislodge.

This same plastic laundry basket was also used as a nursery tank for our small baby Jade perch. Because larger fish will eat baby fry, you’ll need to separate them so an inexpensive basket like this was placed in the fish tank until the fish got larger and able to fend for themselves.

Murray Hallam’s Aquaponics Secrets also covers laundry baskets and other innovative uses including salt baths plus heaps of Aquaponics related information. Get the triple set DVD pack from Murray’s website if you’re interested in learning more about this subject.

5 Comments

Frank, now there is a “problem” I’d like to have, wow. We’ve been up less than three months and only recently been able to plant tomatoes in 2 new GBs. For some reason things at battling along. The grape tomato varieties we chose must really not like something. The Roma tomatoes are showing signs of deficiencies, as too another variety whose leaves have gotten purple areas. Tomatoes are the one crop we’d like to master and get figured out, it is our “primary” for the AP greenhouse, it’s been a bumpy road so far though.

Your post is most encouraging, certainly something I’ll be working towards. Could you share some of the varieties you’ve had good success with? We’re in Canada, I’m sure we’ll find similar varieties.

Shaun it might be a temperature related issue. We are in a subtropical environment and tomatoes do like a lot of warmth. Although we are in a “winter” period at the moment – the days are fine and sunny and there’s enough heat to keep them growing. Tomatoes like a temp between 50F and 90F and if your water is too cold it might be a problem. Try a cultivar suitable for cooler climates. We have grown Romas without problem in Aquaponics but have found the smaller sweet cherry tomatoes and the Amish Paste variety to grow very well and produce good tasting fruit. The larger varieties like Beefstake and Black Russian I didn’t have success with and found them very ordinary and took a long time to ripen. You really do need to trial various strains and rip out the mediocre. Ultimately your climate zone, heat and low humidity, pollination conditions etc can play an important role in success with aquaponics. Climate and access to warmth is so important with growing tomatoes. Might be an idea to see what other gardeners in your locality have had success with and try their suggestions.

Our greenhouse is surprisingly warm, it’s often 5-10 deg C above ambient usually which can push things into the low 30’s. FT water is around 27 deg C. Humidity never goes above 65% – dehumidifier. Things will likely be very different in a few months though, we’re heading into fall soon, and sunlight hours will be a factor. It’s all a first, so we’ve little to go on… no history, which makes things challenging at best.

We’re attending a tomato growing workshop this week, a very knowledgeable farmer will be sharing her wisdom with the group. She grows them both in a greenhouse and outside. I’m sure we’ll learn a ton, including varieties that work in our climate.

Sounds like you have enough warmth in you system Shaun. Our system is now about two and a half years old and growth has come on well over that period. Young aquaponics systems under 12 months do struggle a bit with heavy feeding plants like cabbages, tomatoes etc. You may not have enough fish to provide nutrients. A Nitrate test should alert you to this. Failing that, do add a little potassium hydroxide to assist. http://www.ecofilms.com.au/2011/02/24/are-you-supplying-enough-nutrients/ as fish pellets do not necessarily have all the elements needed for great plant growth. Keep your pH in the mid 6’s and all should be fine. Really its not rocket science. Once its humming along all we do is throw a little bit of lime into the system (a handfull every second week) to buffer the pH down to a more tolerable level (pH 6.8) so fish and plants can live in ideal conditions. And thats about it.

I like to buy seeds that originate in regions with similar climates to the ones that I am attempting to grow in. I feel this gives them an automatic benefit. For example, if I am growing in sandy soil on the hot side of my house, perhaps a mediterannean Roma? Or if I’m growing in a greenhouse, something with more humid origins. I’ve noticed a difference in how much energy I have to exert to help my tomatoes thrive, by being carefully selective of what varieties I use.